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 <h1 class="title">BackedEnum 接口</h1>
 

 <div class="partintro"><p class="verinfo">(PHP 8 &gt;= 8.1.0)</p>


  <div class="section" id="backedenum.intro">
   <h2 class="title">简介</h2>
   <p class="para">
    引擎会自动应用 <span class="classname"><strong class="classname">BackedEnum</strong></span> 接口到回退枚举。
    用户自定义类不能实现该接口。
    由于引擎已提供枚举的默认实现，因此不能重载它的接口。
    主要将它用于类型检测。
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  <div class="section" id="backedenum.synopsis">
   <h2 class="title">接口摘要</h2>


   <div class="classsynopsis">
    <div class="ooclass">
     
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    <div class="classsynopsisinfo">
     <span class="oointerface"><span class="modifier">interface</span> <strong class="interfacename">BackedEnum</strong></span><span class="ooclass">
      <span class="modifier">extends</span>
       <a href="class.unitenum.html" class="classname">UnitEnum</a>
     </span>
     {</div>
    
    <div class="classsynopsisinfo classsynopsisinfo_comment">/* 方法 */</div>
    <div class="methodsynopsis dc-description">
   <span class="modifier">public</span> <span class="modifier">static</span> <span class="methodname"><a href="backedenum.from.html" class="methodname">from</a></span>(<span class="methodparam"><span class="type"><span class="type">int</span>|<span class="type">string</span></span> <code class="parameter">$value</code></span>): <span class="type"><span class="type static">static</span></span></div>
<div class="methodsynopsis dc-description"><span class="modifier">public</span> <span class="modifier">static</span> <span class="methodname"><a href="backedenum.tryfrom.html" class="methodname">tryFrom</a></span>(<span class="methodparam"><span class="type"><span class="type">int</span>|<span class="type">string</span></span> <code class="parameter">$value</code></span>): <span class="type"><span class="type">?</span><span class="type"><span class="type static">static</span></span></span></div>


    <div class="classsynopsisinfo classsynopsisinfo_comment">/* 继承的方法 */</div>
    <div class="methodsynopsis dc-description"><span class="modifier">public</span> <span class="modifier">static</span> <span class="methodname"><a href="unitenum.cases.html" class="methodname">UnitEnum::cases</a></span>(): <span class="type">array</span></div>

   }</div>


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<h2>目录</h2><ul class="chunklist chunklist_reference"><li><a href="backedenum.from.html">BackedEnum::from</a> — 映射标量为 enum 实例</li><li><a href="backedenum.tryfrom.html">BackedEnum::tryFrom</a> — 映射标量为 enum 实例或 null</li></ul>
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